Adolescents in Economically Disadvantaged Urban Environments and Exposure to Tobacco Smoke


Key Points

  • Urine NNAL screening finds a large majority of urban adolescents (94%) are exposed to tobacco smoke.
  • African American adolescents are exposed to higher levels of secondhand smoke than adolescents of other ethnic/racial groups.
  • Secondhand smoke is associated with significant medical morbidity in adolescents. Routine biochemical screening with NNAL or cotinine detects high prevalence of secondhand smoke exposure and should be considered as a tool to reduce secondhand smoke exposure in high-risk populations.

Research shows that secondhand smoke is a major cause of disease, including lung cancer and heart disease, as well as respiratory problems in nonsmokers. In addition, exposure to secondhand smoke increases the likelihood of nonsmokers becoming active smokers.

In a study assessing the impact of exposure to tobacco smoke in adolescents from an economically disadvantaged, largely minority population in San Francisco, the researchers found that 94% of the adolescents screened had measurable levels of a biomarker specific for exposure to tobacco smoke. African Americans in the study were exposed to higher levels of secondhand smoke than adolescents in other minority groups. The study was published by Benowitz et al in Cancer Epidemiology, Biomarkers & Prevention.

Study Methodology

The researchers measured levels of cotinine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in the urine samples collected from 466 adolescents, ages 13 to 19, who had received pediatric care at the Children’s Health Center at Zuckerberg San Francisco General Hospital and Trauma Center. Among these adolescents, 91% had public health insurance and 8% were uninsured; 53% were Latino, 22% were African American, 11% were Asian, and 3% were white.

Urine samples were analyzed for free cotinine and total (free plus conjugated) NNAL by liquid chromatography-tandem mass spectrometry. The lower limit of quantitation (LOQ) for cotinine was 0.05 ng/mL and for NNAL, it was 0.25 pg/mL. Concentrations were analyzed both with and without creatinine normalization.

Study Findings

The researchers found that 94% of the adolescents had measurable levels of NNAL compared with 87% for cotinine. The optimal NNAL cutoff point to distinguish active smoking from secondhand smoke was 9.6 pg/mL by latent class of 14.4 pg/mL by receiver-operating characteristic analysis.

Cotinine and NNAL were strongly correlated, but the correlation slopes differed for active vs secondhand smoke-exposed adolescents. Among nonsmokers, NNAL levels were significantly higher in African American (median, 3.3 pg/mL) compared with other groups (0.9-1.9 pg/mL), suggesting greater exposure to secondhand smoke.

The Need for Public Health Initiatives 

“Our data show nearly ubiquitous exposure to tobacco smoke in this population of economically disadvantaged adolescents, which highlights the need for new public health initiatives to reduce exposure,” said Neal L. Benowitz, MD, Professor of Medicine and Bioengineering & Therapeutic Sciences and Chief of the Division of Clinical Pharmacology at the University of California, San Francisco, and lead author of this study, in a statement. “It also suggests that routine urine screening for NNAL or cotinine, with counseling intervention in those screening positive for exposure, could help address the public health challenge.”

Dr. Benowitz, of the Division of Clinical Pharmacology and Experimental Therapeutics at the University of California, San Francisco, is the corresponding author of this study.

Funding for this study was provided by the Flight Attendant Medical Research Institute Bland Lane Center of Excellence on Secondhand Smoke at the University of California, San Francisco and the National Institutes of Health.

Disclosure: Dr. Benowitz is a consultant/advisory board member for Pfizer, and has served as a paid expert witness in litigation against tobacco companies. No potential conflicts of interest were disclosed by the other study authors.


The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.